Novel photographic products and processes

ABSTRACT

THE PRESENT INVENTION RELATES TO PHOTOGRAPHY AND, MORE PARTICULARLY, TO DIFFUSION TRANSFER PROCESS PHOTOGRAPHIC FILM UNITS WHICH COMPRISE A PHOTOSENSITIVE ELEMENT ADAPTED TO PROVIDE, BY DIFFUSION TRANSFER PHOTOGRAPHIC PROCESSING, SELECTIVE DYE IMAGE RECORDATION OF INCIDENT ACTINIC RADIATION AS A FUNCTION OF THE POINT-TOPOINT DEGREE OF PHOTOSENSITIVE ELEMENT EXPOSURE, WHICH FILM UNIT INCLUDES A PLURALITY OF ESSENTIAL LAYERS INCLUDING A DIRECT NEGATIVE PHOTOSENSITIVE SILVER HALIDE LAYER COMPRISING PHOTOSENSITIVE SILVER HALIDE GRAINS THE MAJORITY OF WHICH POSSESS A SUBSTANTIALLY UNIFORM GRAIN SIZE WITHIN THE RANGE OF $0.5 TO 3.0U HAVING ASSOCIATED THEREWITH DYE IMAGE-FORMING MATERIAL WHICH IS DIFFUSIBLE DURING PROCESSING AS A FUNCTION OF THE POINT-TO-POINT DEGREE OF SILVER HALIDE LAYER EXPOSURE TO INCIDENT ACTINIC RADIATION AND A LAYER ADAPTED TO RECEIVE IMAGE-FORMING MATERIAL DIFFUSING THERETO; AND TO SPECIFIED DIFFUSION TRANSFER PROCESSES EMPLOYING SUCH FILM UNITS.

Oct. 10, 1972 3,697,269

W. J. TIMSON NOVEL PHOTOGRAPHIC PRODUCTS AND PROCESSES Filed Dec. 21, 1970 6 Shee ts-Sheet 1 INVENTOR. WILLIAM J. TIMSON fimw'namdm W 77%. 5nd

ATTORNEYS Oct. 10, 1972 w. J. TIMSON NOVEL PHOTOGRAPHIC PRODUCTS AND PROCESSES Filed Dec. 21, 1970 6 Sheets-Sheet 2 INVENTOR. WILLIAM J. TI MSON amd M 773.5%)

ATTORNEYS W. J. TIMSON NOVEL PHOTOGRAPHIC PRODUCTS AND PROCESSES Filed D96. 21, 1970 6 Sheets-Sheet 3 INVENTOR. WILLIAM J, TIMSON @houm and and MM 7%. 7m

AT TORNE Y5 Oct. 10, 1972 w. J. TIMSON NOVEL PHQTQGRAPHIC PRODUCTS AND PROCESSES Filed Dec. 21, 1970 6 Sheets-Sheet 4 w OE INVENTOR. WILLIAM J. TIMSON Oct. 10, 1972 w. J. TIMSON NOVEL PHOTOGRAPHIC PRODUCTS AND PROCESSES Filed Dec. 21, 1970 6 Sheets-Sheet 5 INVENTOR. WILLIAM J. TIMSON Ema/mi a d, Maui 7/2. 57nd ATTORNEYS Ocli. 10, 1972 w. .J. TIMSON 3,

NOVEL PHOTOGRAPHIC PRODUCTS AND PROCESSES Filed Dec. 21, 1970 6 Sheets-Sheet 6 ALISNBG 31d WVS LNVENTOR. WILLIAM J. TIMSON fimu n and Mu! PM 7/2 59m AT TORNEYS United States Patent Office 3,697,269 Patented Oct. 10, 1972 3,697,269 NOVEL PHOTOGRAPHIC PRODUCTS AND PROCESSES William J. Timson, Belmont, Masst, asslgnor to Polaroid Corporation, Cambridge, Mass. Filed Dec. 21, 1970, Ser. No. 99,970 Int. Cl. G03c 1/48, 5/54, 1/40 US. Cl. 96-3 28 Claims ABSTRACT OF THE DISCLOSURE The present invention relates to photography and, more particularly, to diffusion transfer process photographic film units which comprise a photosensitive element adapted to provide, by diffusion transfer photographic processing, selective dye image recordation of incident actinic radiation as a function of the point-topoint degree of photosensitive element exposure, which film unit includes a plurality of essential layers including a direct negative photosensitive silver halide layer comprising photosensitive silver halide grains the majority of which possess a substantially uniform grain size within the range of -05 to 3.0 having associated therewith dye image-forming material which is diffusible during processing as a function of the point-to-point degree of silver halide layer exposure to incident actinic radiation and a layer adapted to receive image-forming material diffusing thereto; and to specified diffusion transfer processes employing such film units.

BACKGROUND OF THE INVENTION (1) Field of the invention The present invention is directed to providing new and improved diffusion transfer process photographic film units adapted to provide, as a function of the point-topoint degree of photoexposure, by diffusion transfer processing a dye transfer image.

(2) Description of prior art As disclosed in US. Pat. No. 3,415,644, a composite photosensitive structure, particularly adapted for reflection type photographic diffusion transfer color process employment, which comprises a plurality of essential layers including, in sequence, a dimensionally stable opaque layer; one or more silver halide emulsion layers having associated therewith dye imagesproviding material which is soluble and diffusible, in alkali, at a first pH, as a function of the point-to-point degree of its associated silver halide emulsions exposure to incident actinic radiation; a polymeric layer adapted to receive solubilized dye image-providing material diffusing thereto; a polymeric layer containing sufficient acidifying capactiy to effect reduction of a processing composition from the first pH to a second pH at which the dye image-providing material is substantially nondifi'usible; and a dimensionally stable transparent layer, may be exposed to incident actinic radiation and processed by intcrposing, intermediate the silver halide emulsion layer and the reception layer, an alkaline processing composition possessing the first pH and containing opacifying agent, which may reflect incident radiation, in a quantity sufficient to mask dye image-providing material associated with the silver halide emulsion.

In a preferred embodiment, the composite photosensitive structure includes a rupturable container, retaining the alkaline processing composition having the first pH and opacifying agent, fixedly positioned extending transverse a leading edge of the composite structure in order to effect, upon application of compressive pressure to the container, discharge of the processing composition intermediate the opposed surfaces of the reception layer and the next adjacent silver halide emulsion.

The liquid processing composition, distributed intermediate the reception layer and the silver halide emulsion, permeates the silver halide emulsion layers of the composite photosensitive structure to initiate development of the latent images contained therein resultant from photoexposure. As a consequence of the development of the latent images, dye image-providing material associated with each of the respective silver halide emulsion layers is individually mobilized as a function of the point-to-point degree of the respective silver halide emulsion layers photoexposure, resulting in imagewise distributions of mobile dye image-providing materials adapted to transfer, by diffusion, to the reception layer to provide the desired transfer dye image. Subsequent to substantial dye image formation in the reception layer, a sufiicient portion of the ions of the alkaline processing composition transfers, by diffusion, to the polymeric neutralizing layer to effect reduction in the alkalinity of the composite film unit to the second pH at which dye image providing material is substantially nondiffusible, and further dye image-providing material transfer is thereby substantially obviated.

The transfer dye image is viewed, as a reflection image, through the dimensionally stable transparent layer against the background provided by the opacifying agent, distributed as a component of the processing composition, intermediate the reception layer and next adjacent silver halide emulsion layer. The thus-formed opacifying stratum effectively masks residual dye image-providing material retained in association with the silver halide emulsion layer subsequent to processing.

In U.S. Pat. No. 3,415,646 the dimensionally stable layer of the film unit next adjacent the photosensitive silver halide layer or layers is disclosed to be transparent to incident actinic radiation and as disclosed in US. Pat. No. 3,415,645 in such instance the opacifying agent may be initially disposed in the film unit intermediate the reception layer and next adjacent silver halide layer.

As disclosed in the copending US. patent application Ser. No. 846,441 of Edwin H. Land, filed July 31, 1969 now U.S. Pat. No. 3,615,421 issued Oct. 26, 1971 and the copending US. patent application Ser. No. 3646, now abandoned, Sheldon A Buckler, filed Jan. 19, 1970, the opacifying component of the film unit may optionally be initially disposed as a preformed processing composition permeable layer, intermediate the reception layer and next adjacent silver halide layer, in a concentration which prior to photoexposure is insufficent to prevent transmission therethrough of exposing actinic radiation and which, subsequent to processing, possesses an opacifying capacity effective to mask residual dye imageproviding material retained associated with the film units silver halide emulsion layers, and in the copending US. patent application Ser. No. 43,742 of Edwin H. Land, filed 3 June 5, 1970, now US. Pat. 3,647,435, the opacifying component of the film unit may optionally be initially formed in situ, intermediate the reception layer and next adjacent silver halide layer, during photographic processing of the film unit.

In the copending U.S. patent applications of Edwin H. Land, Ser. No. 786,352, filed Dec. 23, 1968, and Ser. No. 43,782, filed June 5, 1970, the opacifying component is disclosed to optionally comprise a light-absorbing reagent such as a dye which is present as an absorbing species at the first pH and which may be converted to a substantially non-absorbing species at the second pH, and in US. Pat. No. 3,473,925 and the copending US. patent applications of Terry W. Milligan and Richard W. Young, Ser. No. 846,177, filed July 30, 1969 now US. Pat. No. 3,573,042 issued Mar. 30, 1971, and Ser. No. 864,397, filed Oct. 7, 1969, now US. Pat. No. 3,576,626 issued Apr. 27, 1971, opacifying and reflecting component, respectively, may be individually interposed intermediate the silver halide layer and reception layer by selective distribution from a composite or a plurality of rupturable containers.

In the copending US. patent application Ser. No. 782,- 056 of Edwin H. Land, filed Dec. 9, 1968 now US. Pat. No. 3,573,043 issued Mar. 30, 1971, the polymeric neutralizing layer is disclosed to be optionally disposed intermediate the dimensionally stable opaque layer and next adjacent essential layer, i.e., next adjacent silver halide/ dye image-providing material component, to effect the designated modulation of film unit's environmental pH; the copending US. patent application Ser. No. 846,442 of Edwin H. Land, filed July 31, 1969 now US. Pat No. 3,576,625 issued Apr. 27, 1971, discloses the employment of particulate acid distributed within the film unit to effect the modulation of the environmental pH, and the copending U.,S. patent application Ser. No. 782,075 of Edwin H. Land, filed Dec. 9, 1968 now US. Pat. No. 3,573,- 044 issued Mar. 30, 1971, discloses the employment of processing composition solvent vapor transmissive dimensionally stable layers to effect process modulation of dye transfer as a function of solvent concentration.

Where desired, the film unit may also be constructed in accordance with the disclosure of the copending US. patent applications of Howard G. Rogers, Ser. No. 39,646, filed May 22, 1970 now US. Pat. No. 3,594,165, issued July 20, 1971, and Ser. No. 39,666, filed May 22, 1970 now U.S. Pat. No. 3,594,164 issued July 20, 1971, to comprise a composite photosensitive structure including a transparent dimensionally stable layer canying a reception layer, a processing composition permeable opaque layer and a photosensitive silver halide layer and the film unit may include a separate dimensionally stable sheet element adapted to be superposed on the surface of the photosensitive structure opposite the dimensionally stable layer and may further include a rupturable container retaining processing composition and adapted to distribute the composition intermediate the sheet and photosensitive structure to effect processing. As further disclosed in the last-cited applications, in structures wherein the receptor is positioned next adjacent the transparent layer or the processing composition and/or the sheet is to be separated from the remainder of the film unit subsequent to processing, the latter elements may optionally include a opacifying component.

As disclosed in copending US. patent application Ser. No. 3645 of Edwin H. Land, filed Jan. 19, 1970 now US. Pat. No. 3,620,724 issued Nov. 16, 1971 and the copending US. Patent application Ser. No. 3691 of Sheldon A. Buckler, filed Ian. 19, 1970, now abandoned, the dimensionally stable layer referred to may be opaque and in which instance the photosensitive silver halide layer is positioned next adjacent the opaque support layer and the opacifying component of the film units processing composition permeable opaque layer will be disposed in the unit in a concentration insufficient to prevent transmission therethrough of exposing actinic radiation and which, subsequent to processing, possesses an opacifying capacity effective to mask residual dye imageproviding material retained associated with the silver halide layer, and as disclosed in the copending US. patent application Ser. No. 43,741 of Edwin H, Land, filed June 5, 1970, now US. Pat. 3,647,434, the opacifying agent may be optionally formed in such film unit, in situ, during processing of the unit.

SUMMARY OF THE INVENTION The present invention is directed to a new and improved, preferably integral negative/positive, difiusion transfer process photographic film unit adapted to provide, by diffusion transfer processing, photographic color image reproduction as a function of exposure of such film unit to incident actinic radiation.

The film unit assemblage construction to be employed in the practice of the present invention preferably comprises a film unit of the general type set forth in aforementioned U.S. Pats. Nos. 3,415,644, 5 and 6 and 3,473,- 925 and copending US. patent applications Ser. Nos. 782,- 056 now US. Pat. No, 3,573,043; 782,075 now US. Pat. No. 3,573,044; 786,352; 846,177 now US. Pat. No. 3,573,- 042; 846,441 now US. Pat. No. 3,615,421; 846,442 now US. Pat. No. 3,576,625; 864,397 now US. Pat. No 3,576,- 626; 3645 now US. Pat. No. 3,620,724; 3691, now abandoned; 39,646 now US. Pat. No. 3,594,165; 39,666 now US. Pat. No. 3,594,164; 43,741; 43,742; and 43,782 and in US. Pats. Nos. 2,983,606 and 3,345,163; and will include a photosensitive silver halide layer which comprises photosensitive silver halide grains the majority of which possess a substantially uniform grain size within the range of -05 to 3.0 disposed in a photosensitive element which contains a plurality of layers including, in relative order, a dimensionally stable layer preferably opaque to incident actinic radiation; one or more photosensitive silver halide layers having associated therewith dye imageforming material which is processing composition diffusible as a function of the point-to-point degree of silver halide layer exposure to incident actinic radiation; a layer adapted to receive image-forming material diffusing thereto; a dimensionally stable layer transparent to incident actinic radiation; and means for interposing, intermediate the silver halide layers and the reception layer, opacitying agent and a processing composition, and, in a particularly preferred embodiment, a processing composition possessing a first pH at which the dye image-forming material is diffusible during processing and means for modulating the pH of the film unit from the first pH to a second pH at which the dye image-forming material is substantally nondifi'usible subsequent to substantial dye transfer image formation.

In accordance with a specifically preferred embodiment of the present invention, a film unit assemblage of the aforementioned general structural parameters will be adapted to be processed, subsequent to photoexposure, in the presence of actinic radiation and may be fabricated to employ, as means interposed intermediate the reception layer and next adjacent silver halide layer subsequent to photoexposure, an inorganic light-reflecting pigment dispersion containing reflecting pigment and at least one optical filter agent, at a pH above the pKa of the optical filter agent and at which pH the dye image-forming material is diffusible during processing as a function of silver halide layer photoexposnre, in a concentration in admixture effective to provide a barrier to transmission of actinic radiation therethrough, and the means for interposing the opacifying agent and the processing composition, a rupturable container, retaining the opacifying agent disposed in the processing composition selected, fixedly positioned extending transverse a leading edge of the film unit and adapted, upon application of compressive pressure, to distribute its contents intermediate the reception layer and next adjacent silver halide layer.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a perspective view of a photographic film unit embodying the invention;

FIGS. 2, 4 and 6 are diagrammatic enlarged cross-sectional views of the film unit of FIG. 1, along section line 2-2, illustrating the association of elements during the three illustrated stages of the performance of a diffusion transfer process, for the production of a multicolor transfer image according to the invention, the thickness of the various materials being exaggerated, and wherein FIG. 2 represents an exposure stage, FIG. 4 represents a processing stage and FIG. 6 represents a product of the process;

FIGS. 3, 5 and 7 are diagrammatic, further enlarged cross-sectional views of the film unit of FIGS. 2, 4 and 6, along section lines 3-3, 5-5 and 7-7, respectively, further illustrating in detail, the arrangement of layers comprising the photosensitive laminate during the three illus' trated stages of the transfer process; and

FIGS. 8 and 9 are graphic representations of the characteristic curves of multicolor dye transfer images of the present invention compared with prior art control transfer images.

DETAILED DESCRIPTION OF THE INVENTION As previously characterized, diffusion transfer photographic processing may be employed to provide a positive reflection dye image, as a direct function of actinic radiation incident on a film unit assemblage which unit is preferably constructed to comprise a plurality of sequential layers including a dimensionally stable layer most preferably opaque to incident radiation; 3. photosensitive silver halide layer having associated therewith dye imageforming material which is processing composition diffusible at a selected first pH as a function of the point-topoint degree of silver halide layer photoexposure; a layer adapted to receive dye image-forming material diffusing thereto; a dimensionally stable layer transparent to incident radiation; means for interposing, intermediate the silver halide layer and the reception layer, opacifying agent and preferably an inorganic reflecting pigment dispersion containing at least one optical filter agent or dye in a concentration effective to provide, subsequent to selective photoexposure of the silver halide layer, protection of the silver halide layer from further exposure to actinic radiation incident on the dimensionally stable layer; means for converting the pH of the film unit from the first pH to a second pH at which the dye image-forming material is substantially nondiffusible subsequent to substantial dye image-forming material diffuson to the reception layer; and wherein the dimensionally stable layers, taken together, possess a processing composition solvent vapor permeability adapted to effect, subsequent to substantial dye transfer image formation and preceding substantial dye transfer image degradation, osmotic transpiration of processing composition solvent in a quantity effective to decrease a first solvent concentration at which the dye image-forming material is soluble and difi'usible as a function of processing to a second solvent concentration at which the dye image-forming material is substantially nondiffusible.

It is now has been discovered, however, that improved photographic reproduction in color by diffusion transfer processing may be accomplished by employment of a diffusion transfer process film unit which comprises a plurality of layers including photosensitive layer comprising photosensitive silver halide grains the majority of which possess a substantially uniform grain size within the range of -05 to 3.0 having associated therewith a dye image-providing material which is difiusible, during processing of the unit, as a function of the point-to-point degree of the photosensitive layer's exposure to incident actinic radiation, and a layer adapted to receive dye imageproviding material diffusing thereto.

In the preferred embodiment of the present invention, \-7S% and most preferably 3 -90% of the photosensitive silver halide grains constituting the photosensitive layer possess a substantially uniform grain size distribution, preferably within :-l0%, by weight, of the selected grain size.

Employment of diffusion transfer color process film units possessing photosensitive silver halide components exhibiting the restricted grain size distribution described has been discovered to provide markedly increased diffusion transfer processing temperature latitude; film unit storage stability; and more efficient and effective utilization of silver, dye image-providing components and photographic adjuvants as, for example, sensitizing dye components of the film unit. Specifically, the employment of the silver halide grain size distribution denoted specifically facilitates the avoidance of the presence as a component of the photosensitive silver halide layer of a substantial proportion or number of grains possessing a diameter ;-3.0 which grains possess, as a function of surface area, a proclivity for formation of undesired fog, which proclivity increases as a direct function of increase in processing temperature, with the concomitant results of less efficient and effective utilization of a selected silver halide concentration per unit weight, degradation of image recordation acuity and corresponding dye transfer image construction. Conversely, the presence of a substantial number of grains possessing a diameter 4-0.5;t is also avoided, such grains having been found to exhibit relatively low effective sensitivity to exposure radiation, thus also resultant in less efficient utilization of silver halide to provide dye transfer image formation as a function of the film units exposure to actinic radiation.

Recognizing that although efficient utilization of silver halide in terms of its active species film unit coverage requirement decreases the excess quantities of silver halide, dye image-providing material and photographic adjuvants necessary to factor out inefficient silver halide grain performance, most importantly control of the imagewise generation of and transfer of dye image-providing material is most accurately accomplished employing a silver halide grain distribution the sum total grains of which are active to individually contribute to selective generation and transfer of the image-providing components.

It has been found that the advantages produced by means of the present invention are facilitated by maximizing restriction of the grain size distribution to the mean grain size selected to provide the results desired. Irrespective of such optimization, however, the photosensitivity response of the grains may be such as to provide a photoresponse gradient traditionally illustrated by the curve shape of the standard H & D type curve integrating processed silver image density as a function of film unit photoexposure.

It will be recognized that the employment of silver halide grain dispersions possessing maximally limited crystal size distribution and the last-mentioned photoresponse characteristics may be readily prepared in a plurality of expeditious manners, including the simple procedure which comprises the blending of dispersions possessing substantially homogeneous or uniform crystal size distributions wherein the silver halide crystal component of the dispersions forming the ultimate blend possesses differential electromagnetic radiation sensitivity.

The photoresponsive silver halide material employed in the practice of the present invention will, as previously described, comprises a crystal of a compound of silver, for example, one or more of the silver halides, such as photosensitive silver chloride, silver iodide, silver bromide, and preferably, mixed silver halides, such as silver chlorobromide, silver iodochloride, silver iodobromide or silver iodochlorobromide, of varying halides ratios and the silver concentrations dispersed in a processing composition permeable binder material such as gelatin and the like, most preferably silver iodobromide and iodochlorobromide, particularly that comprising -0.1 to 9% iodide by weight of silver.

In a particularly preferred embodiment of the present invention, 3-75% and more preferably 5-90% of the photosensitive silver halide grains possess the substantially uniform grain size within the stated range of -0.5 to 3.0a, and most preferably the substantially uniform silver halide grains are within of the selected grain size, i.e., -0.5il0% to 3.0: 10%

The preferred silver halide type photosensitive layers employed for the fabrication of the photographic film unit, may be prepared by reacting a water-soluble silver salt, such as silver nitrate, with at least one water soluble halide, such as ammonium, potassium or sodium chloride, preferably together with corresponding iodide and bromide, in an aqueous solution of a peptizing agent such as colloidal gelatin solution; digesting the dispersion at an elevated temperature, to provide increased crystal growth; washing the resultant dispersion to remove undesirable reaction products and residual water-soluble salts, for example, employing the preferred gelatin matrix material, by chilling the dispersion, noodling the set dispersion, and washing the noodles with cold water, or, alternatively, employing any of the various floc systems, or procedure adapted to effect removal of undesired components, for example, the procedures described in US. Pats. Nos. 2,614,928; 2,614,929; 2,728,662, and the like; after ripening the dispersion at an elevated temperature in combination with the addition of gelatin or such other polymeric material as may be desired and various adjuncts, for example, chemical sensitizing agents of US. Pats. Nos. 1,- 574,944; 1,623,499; 2,410,689; 2,597,856; 2,597,915; 2,- 487,850; 2,518,698; 2,521,926; and the like; all according to the traditional procedures of the art, as described in Neblette, C. B., Photographiy Its Materials and Processes, 6th ed., 1962.

Optical sensitization of the emulsions silver halide crystals may be accomplished by contact of the emulsion composition with an effective concentration of the selected optical sensitizing dyes dissolved in an appropriate dispersing solvent such as methanol, ethanol, acetone, water, and the like; all according to the traditional procedures of the art, as described in Hammer, F. M., The Cyanine Dyes and Related Compounds.

Additional optional additives, such as coating aids, hardeners, viscosity-increasing agents, stabilizers, preservatives, and the like, for example, those set forth hereinafter, also may be incorporated in the emulsion formulation, according to the conventional procedures known in the photographic emulsion manufacturing art.

As the binder for the photoresponsive material, the aforementioned gelatin may be, in whole or in part, replaced with some other natural and/ or synthetic processing composition permeable polymeric material such as albumin; casein; or zein or resins such as cellulose derivative, as described in U.S. Pats. Nos. 2,322,085 and 2,541,474; vinyl polymeric such as described in an extensive multiplicity of readily available US. and foreign patents or the photoresponsive material may be present substantially free of interstitial binding agent as described in US. Pats. Nos. 2,945,771; 3,145,566; 3,142,567; Newman, Comment on Non-Gelatin Film, B. J. O. P., 434, Sept. 15, 1961; and Belgian Pats. Nos. 642,557 and 642,558.

As previously mentioned, photosensitive silver halide emulsions possessing stated grain size distribution may be readily obtained by a plurality of conventional emulsion manufacturing procedures known to those skilled in the art, including procedures and apparatus particularly adapted to provide restricted and substantially homogeneous or uniform grain size distributions; see, for example, the processes and apparatus disclosed in U.S. Pats. Nos. 3,326,641 and 3,415,650, each of which is specifically hereby incorporated herein by reference.

One procedure particularly useful for the production of one preferred gelatino silver halide emulsion possessing a predetermined narrow grain size distribution comprises the formulation, in the'manner previously detailed of a silver iodochlorobromide emulsion containing in order of -2% iodide by initially forming the emulsion, separating from the formulation undesired reaction products, and afterripening the resultant silver iodochlorobromide emulsion in combination with the selected auxiliary sensitizing, speed increasing, etc., adjuncts elected.

Specifically, the specified emulsion may be readily formulated by a conventional double jet addition, over a period of one day, at a rate of 100 cc. per hour per jet, one jet delivering a solution comprising 3 M. silver nitrate, in distilled water, at room temperature, the second jet delivering a solution comprising 3 M. alkali halide (e.g. potassium) possessing 15% bromide, 5% 15% chloride, 2.5:2.4% iodide to equal in distilled water, at room temperature, to a 5% solution of gelatin in distilled water, at room temperature, preadjusted to pH 6 with 5% sodium hydroxide. The resultant silver iodochlorobromide emulsion is held subsequent to formula tion for the period of time required to provide the selected silver halide grain size distribution and separated from the reaction mixture, i.e., the supernatant liquid and washed with chilled distilled water until the wash water exhibits a conductivity of -300 to 500p. mhos./cm., the volume adjusted with distilled water for the addition of 20 gms. of gelatin per 1000 cc. of emulsion, and the emulsion then afterripening for 3 hours at a temperature of 60 C. and a pH of 5.5.

A plurality of the procedures which exist in the art, including those of the last-cited US. patents and application, employ mechanical particle classifier apparatus and techniques adapted to differentially separate materials of varying densities and materials of the same density and varying mass, which are, accordingly, particularly adapted to classify silver halide grains into desired distribution ranges and, at the election of the operator, provide further concentration or dilution of emulsion fluid volume specifically including counter-current centrifugal exchange devices; conventional mechanical centrifugation devices and procedures; in process centrifugal force field extraction employing hydrocyclone devices and procedures, etc., positive sedimentation devices and procedures; and the like.

In preferred embodiments of the present invention, the photosensitive silver halide emulsions employed will be emulsions adapted to provide a Diffusion Transfer Process Exposure Index -50, which Index indicates the correct exposure rating of a diffusion transfer color process at which an exposure meter, calibratedv to the ASA Exposure Index, must be set in order that it give correct exposure data for producing color transfer prints of satisfactorily high quality. The Diffusion Transfer Process Exposure Index is based on a characteristic H & D curve relating original exposure of the photosensitive silver halide emulsions to the respective curve densities forming the resultant transfer image. Thus, the Diffusion Transfer Exposure Index is based on the exposure to which the photosensitive silver halide emulsions, for use in color diffusion transfer processes, must be subjected in order to obtain an acceptable color transfer image by that process and is a direct guide to the exposure setting to be entered in a camera in order to obtain proper exposure of the film unit.

In a preferred embodiment of the present invention, the means for interposing the processing composition selected intermediate the reception layer and the silver halide layer comprises a rupturable container retaining a processing composition comprising the solvent and pH concentrations required fixedly positioned and extending transverse a leading edge of the film unit to effect, upon application of compressive pressure, discharge of the processmg composition intermediate the reception layer and the photosensitive silver halide layer next adjacent. In such embodiment the opacifying agent is preferably disposed within the processing composition, as retained in the rupturable container, for distribution as a component of such composition intermediate the reception and silver halide layers, subsequent to selective exposure of the film unit.

Multicolor images may be obtained using color imageforming components in the diffusion transfer process of the present invention by several techniques. One such technique contemplates obtaining multicolor transfer images utilizing, for example, dye developers as dye imageproviding materials by employment of an integral multilayer photosensitive element, such as is disclosed in my aforementioned US. Pat. No. 3,415,644 wherein at least two selectively sensitized photosensitive strata, superposed on a single support, are processed, simultaneously and without separation, with a single, common image-receiving layer. A suitable arrangement of this type comprises the opaque support carrying a red-sensitive silver halide stratum, a green-sensitive silver halide stratum and a bluesensitive silver halide stratum, said emulsions having associated therewith, respectively, for example, a cyan dye developer, a magenta dye developer and a yellow dye developer. The dye developer may be utilized in the silver halide stratum, for example, in the form of particles, or it may be employed as a layer behind the appropriate silver halide strata. Each set of silver halide strata and associated dye developer strata are disclosed to be optionally separated from other sets by suitable interlayers, for example, by layer of gelatin or polyvinyl alcohol. In certain instances, it may be desirable to incorporate a yellow filter in front of the green-sensitive emulsion and such yellow filter may be incorporated in an interlayer. However, where desirable, a yellow dye developer of the appropriate spectral characteristics and present in a state capable of functioning as a yellow filter may be employed. In such instances, a separate yellow filter may be omitted.

In a preferred embodiment of the present invention, the film unit is specifically adapted to provide for the production of a multicolor dye transfer image and the photosensitive laminate comprises, in order of essential layers, the dimensionally stable opaque layer; at least two selectively sensitized silver halide strata each having dye image-providing material of predetermined color associated therewith, for example, dye developers as detailed above, which are soluble and dilfusible in processing composition as a function of the point-to-point degree of exposure of the respective associated silver halide stratum; a polymeric layer dyeable by the dye image-providing materials; and a dimensionally stable transparent layer.

In view of the fact that the preferred dye image-providing materials comprise dyes which are silver halide developing agents, as stated above, for purposes of simplicity and clarity, the present invention will be further described hereinafter in terms of such dyes, without limitation of the invention to the illustrative dyes denoted, and, in addition the photographic film unit structure will be detailed hereinafter employing the last-mentioned preferred structural embodiment, without limitation of the invention to the preferred structure denoted.

The dye developers, as noted above, are compounds which contain, in the same molecule, both the chromophoric system of a dye and also a silver halide developing function. By a silver halide developing function is meant a grouping adapted to develop exposed silver halide. A preferred silver halide development function is a hydroquinonyl group. Other suitable developing functions include ortho-dihydroxyphenyl and orthoand paraamino substituted hydroxyphenol groups. In general, the development function includes a benzenoid developing function, that is, an aromatic developing group which forms quinonoid or quinone substances when oxidized.

The dye developers are preferably selected for their ability to provide colors that are useful in carrying out subtractive color photography, that is, the previously mentioned cyan, magenta and yellow. The dye developers employed may be incorporated in the respective silver halide emulsion or, in the preferred embodiment, in a separate layer behind the respective silver halide stratum. Specifically, the dye developer may, for example, be in a coating or layer behind the respective silver halide stratum and such a layer of dye developer may be applied by use of a coating solution containing about 0.5 to 8%, by weight, of the respective dye developer distributed in a film-forming natural, or synthetic, polymer, for example, gelatin, polyvinyl alcohol, and the like, adapted to be permeated by the chosen diffusion transfer fluid processing composition.

The silver halide strata comprising the multicolor photosensitive laminate preferably possess predominant spectral sensitivity to separate regions of the spectrum and each has associated therewith a dye which is a silver halide developing agent and is, most preferably, substantially soluble in the reduced form only at a first pH possessing, subsequent to processing, a spectral absorption range substantially complementary to the predominant sensitivity range of its associated emulsion.

In the preferred embodiment, each of the silver halide strata, and its associated dye, is separated from the remaining strata, and their associated dye, by separate alkaline solution permeable polymeric interlayers.

In such preferred embodiment of the invention, the silver halide strata comprises photosensitive silver halide dispersed in gelatin and are about 0.6 to 6 microns in thickness; the dye itself is dispersed in an aqueous alkaline solution polymeric binder, preferably gelatin, as a separate layer about 1 to 7 microns in thickness; the alkaline solution permeable polymeric interlayers, preferably gelatin, are about 1 to 5 microns in thickness; the dyeable polymeric layer is transparent and about 0.25 to 0.4 mil. in thickness; and each of the dimensionally stable opaque and transparent layers are alkaline solution impermeable, processing composition vapor permeable and about 2 to 6 mils. in thickness. It will be specifically recognized that the relative dimensions recited above may be appropriately modified, in accordance with the desires of the operator, with respect to the specific product to be ultimately prepared.

Although in point of fact, the dimensionally stable layers employed in the practice of the present invention may possess a vapor transmission rate of l or less gms./ 24 hrs/ infi/mil, in a preferred embodiment of the present invention, the layers employed will possess a vapor transmission rate for the selected processing composition solvent averaging not less than about 100 gms./24 hrs./ 100 inF/miL, most preferably in terms of the preferred solvent, water, a vapor transmission rate averaging in excess of about 300 gms. of water/24 hrs/100 inF/mil, and may advantageously comprise a microporous polymeric film possessing a pore distribution which does not unduly interfere with the dimensional stability of the layers or, where required, the optical characteristics of such layers. Such pore distribution may comprise, for example, an average pore diameter of from L-20 microns to3- 100 microns and a pore volume of 4-3% to3-7%.

In a particularly preferred embodiment of the present invention, the preferred solvent, water, may be employed in a weight/weight ratio of about 1:10 to 1:20 dye to water at a ratio of about 1:3 to 1:10 liquid permeable polymer to water and most preferably will be fabricated to comprise about 300 to 1300 mgs./ft. liquid permeable polymeric binder material, about 200 to 400 mgs./ft. dye and about 5000 mgsjft? water.

The dimensionally stable layers are designed so that there is no liquid flow through the layers while allowing the vapor of the processing composition solvent to pass by diffusion from the evaporating liquid body and the 0perational efliciency of the film unit is directly dependent upon the nature and quality of the vapor permeable membrance characteristics of the layers selected. The vapor transmission characteristics desired are directed to maximization of the rate at which the required quantity of processing solvent is effectively evacuated from the film unit subsequent to substantial dye transfer image formation by diffusion transfer processing, commensurate with maintaining the liquid impermeability and dimensional stability characteristcs of the layers. Thus, the layers should possess the maximum vapor transmission capacity which permits the passage of processing composition solvent vapor, and any gas dissolved therein, at its vapor pressure, without allowing passage of fluid processing composition. The layers employed in accordance with the present invention therefor should be as thin as possible for solvent vapor transmission efliciency yet retain sufficient strength to provide stability to and resist chemical and physical degradation of the film unit under conditions of use.

In the preferred embodiment of the present inventions film unit for the production of a multicolor transfer image, the respective silver halide/dye developer units of the photo-sensitive element will be in the form of a tripack configuration which will ordinarily comprise a cyan dye developer/red-sensitive emulsion unit contiguous the dimensionally stable opaque layer, the yellow dye developer/blue-sensitive emulsion unit most distant from the opaque layer and the magenta dye developer/green-sensitive emulsion unit intermediate those units, recognizing that the relative order of such units may be varied in accordance with the desires of the operator.

Reference is now made to FIGS. 1 through 7 of the drawings wherein there is illustrated a preferred film unit of the present invention and wherein like numbers, appearing in the various figures, refer to like components.

As illustrated in the drawings, FIG. 1 sets forth a perspective view of the film unit, designated 10, and each of FIGS. 2 through 7 illustrate diagrammatic cross-sectional views of film unit 10, along the stated section lines 2-2, 3-3, 5-5, 77, during the various depicted stages in the performance of a photographic diffusion transfer process as detailed hereinafter.

Film unit 10 comprises rupturable container 11, retaining, prior to processing, aqueous processing composition 12, and photosensitive laminate 13 including, in order, dimensionally stable opaque layer 14, preferably an actinic radiation-opaque flexible sheet material; cyan dye developer layer 15; red-sensitive silver halide emulsion layer 16-, interlayer 17; magenta dye developer layer 18; green-sensitive silver halide emulsion layer 19; interlayer 20; yellow dye developer layer 21; blue-sensitive silver halide emulsion layer 22; auxiliary layer 23, which may contain an auxiliary silver halide developing agent; imagereceiving layer 24; spacer layer 25; neutralizing layer 26; and dimensionally stable transparent layer 27, preferably an actinic radiation transmissive flexible sheet material.

The structural integrity of laminate 13 may be maintained, at least in part, by the adhesive capacity exhibited between the various layers comprising the laminate at their opposed surfaces. However the adhesive capacity exhibited at an interface intermediate image-receiving layer 24 and the silver halide emulsion layer next adjacent thereto, for example, image-receiving layer 24 and auxiliary layer 23 as illustrated in FIGS. 2 through 7, should be less than that exhibited at the interface between the opposed surfaces of the remainder of the layers forming the laminate, in order to facilitate distribution of processing solution 12 intermediaee the stated image-receiving layer 24 and the silver halide emulsion layer next adjacent thereto. The lamin-ates structural integrity may also be enhanced or provided, in whole or in part, by providing a binding member extending around, for example, the edges of laminate 13, and maintaining the layers comprising the laminate intact, except at the interface between layers 23 and 24 during distribution of processing composition 12 intermediate those layers. As illustrated in the figures, the binding member may comprise a pressure-sensitive tape 28 securing and/or maintaining the layers of laminate 13 together at its respective edges. Tape 28 will also act to maintain processing solution 12 intermediate imagereceiving layer 24 and the silver halide emulsion layer next adjacent thereto, upon application of compressive pressure to pod 11 and distribution of its contents intermediate the stated layers. Under such circumstances, binder tape 28 will act to prevent leakage of fluid processing composition from the film units laminate during and subsequent to photographic processing.

Rupturable container 11 may be of the type shown and described in any of US. Pats. Nos. 2,543,181; 2,634,886; 3,653,732; 2,723,051; 3,056,492; 3,056,491; 3,152,515; and the like. In general, such containers will comprise a rectangular blank of fluidand air-impervious sheet material folded longitudinally upon itself to form two walls 29 which are sealed to one another along their longitudinal and end margins to form a cavity in which processing composition 12 is retained. The longitudinal marginal seal 30 is made weaker than the end seals 31 so as to become unsealed in response to the hydraulic pressure generated within the fluid contents 12 of the container by the application of compressive pressure to walls 29 of the container.

As illustrated in FIGS. 1, 2 and 3, container 11 is fixedly positioned and extends transverse a leading edge of photosensitive laminate 13 whereby to effect unidirectional discharge of the containers contents 12 between image-receiving layer 24 and the stated layer next adjacent thereto, upon application of compressive force to container 11. Thus, container 11, as illustrated in FIG. 2, is fixedly positioned and extends transverse a leading edge of laminate 13 with its longitudinal marginal seal 30 directed toward the interface between image-receiving layer 24 and auxiliary layer 23. As shown in FIGS. 1, 2 and 4, container 11 is fixedly secured to laminate 13 by extension 32 of tape 28 extending over a portion of one wall 29 of the container, in combination with a separate retaining member such as illustrated retaining tape 33 extending over a portion of laminate 13s surface generally equal in area to about that covered by tape 28.

As illustrated in FIGS. 1, 2 and 4, extension flap 32 of tape 28 is preferably of such area and dimensions that upon, for example, manual separation of container 11 and tape 33, subsequent to distribution of processing composition 12, from the remainder of film unit 10, flap 32 may be folded over the edge of laminate 13, previously covered by tape 33, in order to facilitate maintenance of the laminates structural integrity, for example, during the flexations inevitable in storage and use of the processed film unit, and to provide a suitable mask or frame, for viewing of the transfer image through the picture viewing area of transparent layer 27.

The fluid contents of the container preferably comprise an aqueous alkaline solution having a pH and solvent concentration at which the dye developers are soluble and diffusible and contains inorganic light-reflecting pigment and at least one optical filter agent at a pH above the pKa of such agent in a quantity sufficient, upon distribution, effective to provide a layer exhibiting optical transmission density -6.0 and optical reflection density -l.0 to prevent exposure of photosensitive silver halide emulsion layers 16, 19 and 22 by actinic radiation incident on dimensionally stable transparent layer 27 during processing in the presence of such radiation and to afford immediate viewing of dye image formation in image-receiving layer 24 during and subsequent to dye transfer image formation. Accordingly, the film unit may be processed, subsequent to distribution of the composition, in the presence of such radiation, in view of the fact that the silver halide emulsion or emulsions of laminate are appropriately protected by incident radiation, at one major surface of the opaque processing composition and at the remaining major surface by the dimensionally stable opaque layer. If the illustrated binder tapes are also opaque, edge leakage of actinic radiation incident on the emulsion or emulsions will also be prevented.

The selected reflecting pigment should be one providing a background suitable for viewing the dye developer transfer image formed in the dyeable polymeric layer. In general, while substantially any reflecting agent may be employed, it is preferred that a reflecting agent be selected that will not interfere with the color integrity of the dye transfer image, as viewed by the observer, and, most preferably, an agent which is aesthetically pleasing to the viewer and does not provide a background noise signal degrading, or detracting from, the information content of the image. Particularly desirable reflecting agents will be those providing a white background, for viewing the transfer image, and specifically those conventionally employed to provide background for reflection photographic prints and, especially those agents possessing the optical properties desired for reflection of incident radiation.

As examples of reflecting pigments adapted for employment in the practice of the present invention, mention may be made of barium sulfate, zinc sulfide, titanium dioxide, barium stearate, silver flake, silicates, alumina, zirconium oxide, zirconium acetyl acetate, sodium zirconium sulfate, kaolin, mica, and the like.

A particularly preferred reflecting agent comprises titanium dioxide due to its highly effective reflection properties. In general, in such preferred embodiment, based upon percent titanium dioxide (weight/volume) a processing composition containing about 1500 to 4000 mgs./ ft. titanium dioxide dispersed in 100 cc. of water will provide a percent reflectance of about 85 to 90%. In the most preferred embodiments, the percent reflectance particularly desired will be in the order of -85%.

In embodiments wherein the dispersion comprises a preformed layer positioned intermediate the reception layer and next adjacent silver halide layer, the pigment layer will be sufliciently transparent to allow transit of exposing radiation through the pigment layer and may comprise titanium dioxide reflecting agent possessing a particle size distribution averaging -0.2 micron in diameter and preferably -0.05 micron in diameter as initially present preceding exposure of the film unit, which preferred materials, upon contact with aqueous alkaline processing composition, preferably aggregate to provide particles possessing a diameter -0.2 micron in diameter and will be coated at a coverage of -200 to 1000 mgs./ft. Specifically, the reflecting agent will be present in a quantity insufiicient to prevent exposure of the emulsion layers by actinic radiation incident on the dimensionally stable transparent layer of the film unit but in a concentration sufficient, subsequent to processing, to mask dye developer associated with the silver halide emulsion strata from the dye transfer image. In the preferred construction of such embodiment, the pigment such as titanium dioxide will be initially present in a relatively small particle size to provide unexpectedly efficient transit of radiation through the reflecting layer during exposure which upon contact with an alkaline processing composition and aggregation of the pigment particles provides eflicient light reflectivity and masking capacity subsequent to such aggregation.

In general, the reflecting agents to be employed are those which remain substantially immobile within their respective compositions during and subsequent to photographic processing and particularly those which comprise insoluble and nondiflusible inorganic pigment dispersions within the layer in which they are disposed.

Where desired, reflecting agent pigment may thus be distributed in whole or in part within a processing composition permeable polymeric matrix such as gelatin and/ or any other such polymeric matrixes as are specifically denoted throughout the specification as suitable for employment as a matrix binder and may be distributed in one of more of the film unit layers which may be separated or contiguous, intermediate the image-receiving layer and next adjacent silver halide layer, provided that its distribution and concentration is effective to provide the denoted post processing masking function, and/or in whole or in part the reflecting agent may be ultimately disposed within the processing composition residuum located intermediate the image-receiving layer and next adjacent silver halide emulsion strata and associated dye image-forming material.

The optical filter agent selected should be one exhibiting, at a pH above its pKa, maximum spectral absorption of radiation at the wavelengths to which the film unit's photosensitive silver halide layer or layers are sensitive and should be substantially immobile or nondiffusible within the pigment dispersion, during performance of its radiation filtration function, in order to maintain and enhance the optical integrity of the dispersion as a radiation filter unit functioning in accordance with the present invention, and to prevent its diffusion into and localized concentration within the image-receiving layer thereby decreasing the efliciency of the reflecting pigment dispersion as a background against which image formation may be immediately viewed, during the initial stages in the diffusion transfer processing of the film unit, by filter agent absorption of dispersion reflected visible radiation prior to reduction in the environmental pH below the pKa of the agent. Commensurate with the spectral sensitivity range of the associated silver halide layer or layers, the optical filter agent selected may comprise one or more filter dyes possessing absorption complementary to such silver halide layers in order to provide effective protection against physical fog providing radiation during processing. Recognizing that the filter agent absorption will derogate from imageviewing characteristics by contaminating reflecting pigment background, the selected agents should be those exhibiting major spectral absorption at the pH at which processing is eifected and minimal absorption at a pH below that which obtains during transfer image formation. Accordingly, the selected optical filter agent or agents should possess a pKa below that of the processing pH and above that of the environmental pH subsequent to transfer image formation. and will be preferably selected for employment in the minimum concentration necessary to provide an optical transmission density ;-6.0, at wavelengths at which the silver halide layer is maximally responsive, and an optical reflection density L-l.0 at such wavelengths.

As specific examples of such pH-sensitive optical filter agents adapted for employment in the practice of the present invention, reference is directed to the agents set forth in aforementioned copending US. patent application Ser. No. 43,782, filed June 5, 1970, incorporated herein by reference.

In general, preferred agents, both opacifying and filter, are those which remain immobile within their respective compositions during and subsequent to photographic processing and particularly those which comprise insoluble and nondiifusible materials.

As disclosed in the previously cited patents, the liquid processing composition referred to for elTecting multicolor diflusion transfer processes comprises at least an aqueous solution of an alkaline material, for example, diethylamine, sodium hydroxide or sodium carbonate and the like, and preferably possessing a pH in excess of 12, and most preferably includes a viscosity-increasing compound constituting a film-forming material of the type which, when the composition is spread and dried, forms a relatively firm and relatively stable film. The preferred film-forming materials disclosed comprise high molecular weight polymers such as polymeric, water-soluble ethers which are inert to an alkaline solution such as, for example. a hydroxyethyl cellulose or sodium carboxymethyl cellulose. Additionally, film-forming materials or thickening agents whose ability to increase viscosity is substantially unaffected if left in solution for a long period of time are also disclosed to be capable of utilization. As stated, the film-forming material is preferably contained in the processing composition in such suitable quantities as to impart to the composition a viscosity in excess of 100 cps. at a temperature of approximately 24 C. and preferably in the order of 100,000 cps. to 200,000 cps. at that temperature.

In the performance of a diffusion transfer multicolor process employing film unit 10, the unit is exposed to radiation, actinic to photosensitive laminate 13, incident on the laminates exposure surface, as illustrated in FIG. 3.

Subsequent to exposure, as illustrated by FIGS. 2 and 4, film unit is processed by being passed through opposed suitably gapped rolls 35 in order to apply compressive pressure to frangible container 11 and to effect rupture of longitudinal seal 30 and distribution of alkaline processing composition 12, possessing inorganic light-reflecting pigment and optical filter agent at a pH above the pKa of the filter agent and a pH at which the cyan, magneta and yellow dye developers are soluble and ditfusible as a function of the point-to-point degree of exposure of red-sensitive silver halide emulsion layer 16, green-sensitive silver halide emulsion layer 19 and blue-sensitive silver halide emulsion layer 22, respectively, intermediate reflecting agent precursor layer 25 and auxiliary layer 23.

Alkaline processing composition 12. permeates emulsion layers 16, 19 and 22 to initiate development of the latent images contained in the respective emulsions. The cyan, magenta and yellow dye developers, of layers 15, 18 and 21, are immobilized, as a function of the development of their respective associated silver halide emulsions, preferably substantially as a result of their conversion from the reduced form to their relatively insoluble and nonditfusible oxidized form, thereby providing imagewise distributions of mobile, soluble and ditfusible cyan, magenta and yellow dye developer, as a function of the point-to-point degree of their associated emulsions exposure. At least part of the imagewise distributions of mobile cyan, magenta and yellow dye developer transfers, by diffusion, to dyeable polymeric layer 24 to provide a multicolor dye transfer image to that layer which is viewable against the background provided by the reflecting pigment present in processing composition residuum 12 masking cyan, magenta and yellow dye developer remaining associated with blue-sensitive emulsion layer 22, green-sensitive emulsion layer 19 and red-sensitive emulsion layer 16. Subsequent to substantial transfer image formation, a sulficient portion of the ions comprising aqueous allgaline processing composition 12 transfer, by diffusion, through permeable polymeric reception layer 24, permeable spacer layer 25 to polymeric neutralizing layer 26 whereby the environmental pH of the system decreases as a function of neutralization to a pH at which the cyan, magenta and yellow dye developers, in the reduced form, are substantially nonditfusible to thereby provide a stable multicolor dye transfer image and discharge of the pH-sensitive optical filter agent by reduction of the pH substantially below the pKa of such agent to thereby provide maximum reflectivity in terms of the pigment concentration present.

The alkaline solution component of the processing composition, positioned intermediate the photosensitive element and the image-receiving layer, thus permeates the emulsions to initiate development of the latent images contained therein. The respective associated dye developers are mobilized in unexposed areas as a consequence of the development of the latent images. This mobilization is apparently, at least in part, due to a change in the solubility characteristics of dye developer upon oxidation and especially as regards its solublility in alkaline solutions. It may also be due in part to a tanning effect on the emulsion by oxidized developing agent, and in part to a localized exhaustion of alkali as a result of development. In unexposed and partially exposed areas of the emulsions, the associated dye developer is diflusible and thus provides an imagewise distribution of unoxidized dye developer dissolved in the liquid processing composition, as a function of the pointto-point degree of exposure of the silver halide emulsion. At least part of this imagewise distribution of unoxidized dye developer is transferred, by imbibition, to a superposed image-receiving layer or element, said transfer substantially excluding oxidized dye developer. The imagereceiving element receives a depthwise diffusion, from the developed emulsion, of unoxidized dye developer without appreciably disturbing the imagewise distribution thereof to provide the reversed or positive color image of the developed image.

Subsequent to distribution of processing composition 12, container 11 may be manually dissociated from the remainder of the film unit, as described above, to provide the product illustrated in FIG. 6.

The present invention will be further illustrated and detailed in conjunction with the following illustrative constructions which set out representative embodiments and photographic utilization of the novel photographic film units of this invention, which, however, are not limited to the details therein set forth and are intended to be illustrative only.

Film units similar to that shown in the drawings may be prepared, for example, by coating, in succession, on a 5 mil. opaque polyester film base, the following layers:

(1) A layer of the cyan dye developer dispersed in gelatin and coated at a coverage of -98 rugs/ft. of dye and -92 mgs./ft. of gelatin;

(2) A red-sensitive gelatino-silver iodochlorobromide emulsion 95 of the silver iodochlorobromide grains of which possess a diameter of 1.8 a: 10% coated at a coverage of mgs./ft. of silver and -27 mgs./ft. of gelatin;

(3) A layer of butyl acrylate/diacetone acrylamide/ styrene/methacrylic acid (60/30/4/6) and polyacrylamide coated in a ratio of -29: 1, respectively, at a coverage of -80 mgsJftF;

(4) A layer of the magenta dye developer OC H1 NO,

QTMQ

C-CHrCH and the auxiliary developer 4'-methylpheny1 hydroquinone dispersed in gelatin and coated at a coverage of -81 mgs./ft. of dye, -15 mgs./ft. of auxiliary developer and 54 mgs./ft. of gelatin;

(8) A blue-sensitive gelatino-silver iodochlorobromide emulsion 95% of the silver iodochlorobromide grains of which possess a diameter of 1-1fl-i'l0% coated at a coverage of -65 mgs./ft.= of silver and -33 mgs./ft. of gelatin; and

(9) A layer of gelatin coated at a coverage of -45 mgs./ft. of gelatin.

Then a transparent mil polyester film base may be coated, in succession, with the following illustrative layers:

(1) A 7:3 mixture, by weight, of polyethylene/maleic acid copolymer and polyvinyl alcohol at a coverage of about 1400 mgsjftfi, to provide a polymeric acid layer;

(2) A graft copolymer of acrylamide and diacetone acrylamide on a polyvinyl alcohol backbone in a molar ratio of 1:3.2z1 at a coverage of about 800 mgsJftF, to provide a polymeric spacer layer; and

(3) A 2:1 mixture, by weight of polyvinyl alcohol and poly-4-vinylpyridine, at a coverage of about 900 mgs./ft. and including about 20 mgs./ft. phenyl mercapto tetravole, to provide a polymeric image-receiving layer.

The two components thus prepared may then be taped together in laminate form, at their respective edges, by means of a pressure-sensitive binding tape extending around, in contact with, and over the edges of the resultant laminate.

18 A rupturable container comprising an outer layer of lead foil and an inner liner or layer of polyvinyl chloride retaining an aqueous alkaline processing solution comprising:

Grns.

Potassium hydroxide 11.20 Hydroxyethyl cellulose (high viscosity) [commercially available from Hercules Powder (30., Wilmington, Delaware, under the trade name Natrasol 250] 3.40

N-phenylethyl-a-picolinium bromide 2.70

Benzotriazole 1.15

Titanium dioxide 50.00

Water, 100.00 cc.

may then be fixedly mounted on the leading edge of each of the laminates, by pressure-sensitive tapes interconnecting the respective containers and laminates, such that, upon application of compressive pressure to a container, its contents may be distributed, upon rupture of the containers marginal seal, between the polymeric image-receiving layer and next adjacent gelatin layer.

The photosensitive composite film units may be exposed through radiation incident on the transparent cellulose triacetate layer and processed by passage of the exposed film units through appropriate pressure-applying members, such as suitably gapped, opposed rolls, to effect rupture of the container and distribution of its contents. Subsequent to processing, the multicolor dye transfer image formation may be viewed through the transparent polyester layer against the titanium dioxide background provided by distribution of the pigment containing processing composition between layer 9 and the polymeric image-receiving layer. Multicolor dye transfer image formation will be found to be substantially completed and exhibiting the required color brilliance, hues, saturation and isolation, within a period of approximately seconds.

For purposes of illustrating the advantageous results achieved by reason of the present invention, film units, fabricated essentially as denoted above, were processed in the stated manner, at processing temperatures of and 40 F., in combination with appropriate control film units, of the same general structure, which specifically comprised conventional blue-, greenand red-sensitive gelatino silver iodochlorobromide emulsions possessing prior art silver halide grain random particle size distributions.

Specially, the film units, both the control and test units, were exposed to a conventional step wedge to provide the graphic illustration of the characteristic curves of the respective dye transfer images, forming the multicolor dye positive images, set forth in FIGS. 8 and 9.

The detailed characteristic curves were determined by plotting the density of the respective images to red, green and blue light, as a function of the log exposure of the photosensitive element, wherein FIG. 8 represents the characteristic curves of test and control film units processed at 40 F. and FIG. 9 represents the characteristic curves of test and control film units processed at 100 F.

Curves A, B and C of FIGS. 8 and 9, respectively, represent the characteristic cyan, magenta and yellow trans fer image dye curves (read to red, green and blue reflected light) of the test film units and Curves D, E and F, respectively, represent the corresponding curves of the control film units.

As will be expressly noted from examination of the respective curves, the previously described significant improvement in dye transfer image control and processing temperature latitude is directly achieved by means of the present invention.

The gelatino silver iodochlorobromide emulsions employed will possess the silver halide distribution gradient detailed hereinbefore and may be prepared as previously detailed and chemically sensitized, at about 56 0, pH 5 and pAg 9, by the addition of a sensitizing amount of a solution containing 0.1 gram of ammonium thiocyanate in 9.9 cc. of water and 1.2 cc. of a solution containing 0.097 gram of gold chloride in 9.9 cc. of water, and a 0.02% aqueous sodium thiosulfate solution. The resultant emulsions may then be appropriately sensitized spectrally by addition of an effective concentration of one or more optical sensitizing dyes dispersed in an appropriate carrier solvent.

By addition of (A) 2.08 gms.

a O I n-CnHu i (B) 0.52 gms.

OH OH uHu-s and (C) 1.18 gms.

HIP-Orb CHrN-CnHzr-ll CH:NCmHn-n l -OH3 to the processing composition, image formation may be immediately viewed upon distribution of the processing composition by reason of the protection against incident radiation afforded the photosensitive silver halide emulsion layers by the compositions optical transmission density of -6.0 density units and against the titanium dioxide's effective reflective background afforded by reason of the composition possessing an optical reflection density -l.0 density units.

The pH and solvent concentration of the alkaline processing solution initially employed will possess a pH above the pKa of the optical filter agents where the latter are employed, that is, the pH at which about 50% of the agents are present as the lesser absorbing species and about 50% are present as the greater absorbing species,

preferably a pKa of -ll and most preferably -l2 and a pH at which the dye developers employed are soluble and difiusible. Although it has been found that the specific pH to be employed may be readily determined empirically for any dye developer and optical filter agent, or group of dye developers and filter agents, most particularly desirable dye developers are soluble at pHs above 9 and relatively insoluble at pHs below 9, in reduced form, and relatively insoluble at substantially any alkaline pH, in oxidized form, and the system can be readily balanced accordingly for such dye developers. In addition, although as previously noted, the processing composition, in the preferred embodiment, will include the stated filmforming viscosity-increasing agent, or agents, to facilitate spreading of the composition and to provide maintenance of the spread composition as a structurally stable layer of the laminate, subsequent to distribution, it is not necessary that such agent be employed as a component of the composition.

Neutralizing means, for example, a polymeric acid layer of the type discussed above may be incorporated, as stated, in the film unit of the present invention, to provide reduction of the alkalinity of the processing solution from a pH above the pKa of the optical filter agent selected at which the dyes are soluble to a pH below the pKa of the agent at which the dyes are substantially nondiffusible, in order to advantageously further stabilize and optimize reflectivity of the dye transfer image. In such instance, the neutralizing layer may comprise particulate acid reacting reagent disposed within the film unit or a polymeric acid layer, for example, a polymeric acid layer approximating 0.3 to 1.5 mils. in thickness, positioned intermediate the transparent support and image-receiving layer, and/or the opaque support and next adjacent emulsion/ dye unit layer, and the film unit may also contain a polymeric spacer or barrier layer, for example, approximating 0.1 to 0.7 mil. in thickness, next adjacent the polymeric acid layer, opposite the respective support layer, as previously described.

Specifically, the film units may employ the presence of a polymeric acid layer such as, for example, of the type set forth in US. Pat. No. 3,362,819 which, most preferably, includes the presence of an inert timing or spacer layer intermediate the polymeric acid layer carried on a support and the image-receiving layer.

As set forth in the last-mentioned patent, the polymeric acid layer may comprise polymers which contain acid groups, such as carboxylic acid and sulfonic acid groups, which are capable of forming salts with alkali metals, such as sodium, potassium, etc., or with organic bases, particularly quaternary ammonium bases, such as tetramethyl ammonium hydroxide, or potentially acidyielding groups, such as anhydrides or lactones, or other groups which are capable of reacting with bases to capture and retain them. The acid-reacting group is, of course, retained in the polymer layer. In the preferred embodiments disclosed, the polymer contains free carboxyl groups and the transfer processing composition employed contains a large concentration of sodium and/or potassium ions. The acid polymers stated to be most useful are characterized by containing free carboxyl groups, being insoluble in water in the free acid form, and by forming water-soluble sodium and/or potassium salts. One may also employ polymers containing carboxylic acid anhydride groups, at least some of which preferably have been converted to free carboxyl groups prior to imbibition. While the most readily available polymeric acids are derivatives of cellulose or of vinyl polymers, polymeric acids from other classes of polymers may be used. As examples of specific polymeric acids set forth in the application, mention may be made of dibasic acid half-ester derivatives of cellulose which derivatives contain free carboxyl groups, e.g., cellulose acetate hydrogen phthalate, cellulose acetate hydrogen glutarate, cellulose acetate hydrogen succinate, ethyl cellulose hydrogen succinate, ethyl cellulose acetate hydrogen succinate, cellulose acetate hydrogen succinate hydrogen phthalate; ether and ester derivatives or cellulose modified with sulfoanhydrides, e.g., with ortho-sulfobenzoic anhydride; polystyrene sulfonic acid; carboxymethyl cellulose; polyvinyl hydrogen phthalate; polyvinyl acetate hydrogen phthalate; polyacrylic acid; acetals of polyvinyl alcohol with carboxy or sulfo substituted aldehydes, e.g., m-, or pbenzaldehyde sulfonic acid or carboxylic acid; partial esters of ethylene/maleic anhydride copolymers; partial esters of methyl-vinyl ether/maleic anhydride copolymers; etc.

As previously noted, the pH of the processing composition preferably is of the order of at least 12 to 14 and the pKa of the selected optical filter agents will accordingly preferably be in the order of 13 or greater. The polymer layer is disclosed to contain at least sufficient acid groups to effect a reduction in the pH of the image layer from a pH of about 12 to 14 to a pH of at least 11 or lower at the end of the imbibition period, and preferably to a pH of about to 8 Within a short time after imbibition, thus requiring, of course, that the action of the polymeric acid be accurately so controlled as not to interfere with either development of the negative or image transfer of unoxidized dye developers. For this reason, the pH of the image layer must be kept at a functional transfer level, for example, 12 to 14 until the dye image has been formed after which the pH is reduced very rapidly to a pH below that at which dye transfer may be accomplished, for example, at least about 11 and preferablyabout pH 9 to 10. Unoxidized dye developers containing hydroquinonyl developing radicals diffuse from the negative to the positive as the sodium or other alkali salt. The diffusion rate of such dye image-forming components thus is at least partly a function of the alkali concentration, and it is necessary that the pH of the image layer remain on the order of, for example, 12 to 14 until transfer of the necessary quantity of dye has been accomplished. The subsequent pH reduction, in addition to its desirable effect upon image light stability, serves a highly valuable photographic function by substantially terminating further dye transfer.

In order to prevent premature pH reduction during transfer processing, as evidenced, for example, by an undesired reduction in positive image density, the acid groups are disclosed to be so distributed in the polymer layer that the rate of their availability to the alkali is controllable, e.g., as a function of the rate of swelling of the polymer layer which rate in turn has a direct relationship to the diffusion rate of the alkali ions. The desired distribution of the acid groups in the polymer layer may be effected by mixing acid polymer with a polymer free of acid groups, or lower in concentration of acid groups, and compatible therewith, or by using only an acid polymer but selecting one having a relatively lower proportion of acid groups. These embodiments are illustrated, respectively, in the cited copending application, by (a) a mixture of cellulose acetate and cellulose acetate hydrogen phthalate and (b) a cellulose acetate hydrogen phthalate polymer having a much lower percentage of phthayl groups than the first-mentioned cellulose acetate hydrogen phthalate.

It is also there disclosed that the layer containing the polymeric acid may contain a Water-insoluble polymer, preferably a cellulose ester, which acts to control or modulate the rate at which the alkali salt of the polymer acid is formed. As examples of cellulose esters contemplated for use, mention is made of cellulose acetate, cellulose acetate butyrate, etc. The particular polymers and combinations of polymers employed in any given embodiment are, of course, selected so as to have adequate wet and dry strength and when necessary or desirable, suitable subcoats are employed to help the various polymeric layers adhere to each other during storage and use.

The inert spacer layer of the last-mentioned patent, for example, an inert spacer layer comprising polyvinyl alcohol or gelatin acts to time" control the pH reduction by the polymeric acid layer. This timing is disclosed to be a function of the rate at which the alkali diffuses through the inert spacer layer. It is there stated to have been found that the pH does not drop until the alkali has passed through the spacer layer, i.e., the pH is not reduced to any significant extent by the mere diffusion into the interlayer, but the pH drops quite rap-idly once the alkali diffuses through the spacer layer.

As disclosed in aforemtioned U.S. Pat. No. 3,362,819, the presence of an inert spacer layer was found to be effective in evening out the various reaction rates over a wide range of temperatures, for example, by preventing premature pH reduction when imbibition is effected at temperatures above room temperature, for example, at to F. By providing an inert spacer layer, that application discloses that the rate at which alkali is available for capture in the polymeric acid layer becomes a function of the alkali diffusion rates.

However, as disclosed in US. Pat. No. 3,455,686 preferably the aforementioned rate at which the cations of the alkaline processing composition, i.e., alkali ions, are available for capture in the polymeric acid layer should be decreased with increasing transfer processing temperatures in order to provide diffusion transfer color processes relatively independent of positive transfer image variations over an extended range of ambient temperatures.

Specifically, it is there stated to have been found that the diffusion rate of alkali through a permeable inert polymeric spacer layer increases with increased processing temperature to the extent, for example, that at relatively high transfer processing temperatures, that is, transfer processing temperatures above approximately 80 F., a premature decrease in the pH of the transfer processing composition occurs due, at least in part, to the rapid diffusion of alkali from the dye transfer environment and its subsequent neutralization upon contact with the polymeric acid layer. This was stated to be especially true of alkali traversing an inert spacer layer possessing permeability to alkali optimized to be effective with the temperature range of optimum transfer processing. Conversely, at temperatures below the optimum transfer processing range, for example, temperatures below approximately 40 F., the last-mentioned inert spacer layer was disclosed to provide an effective diffusion barrier timewise preventing effective traverse of the inert spacer layer by alkali having temperature depressed diffusion rates and to result in maintenance of the transfer processing environments high pH for such an extended time interval as to facilitate formation of transfer image stain and its resultant degradation of the positive transfer images color definition.

It is further stated in the last-mentioned US. Pat. No. 3,455,686 to have been found, however, that if the inert spacer layer of the print-receiving element is replaced by a spacer layer which comprises a permeable polymeric layer exhibiting permeability inversely dependent on temperature, that is, a polymeric film-forming material which exhibits decreasing permeability to solubilized alkali derived cations such as alkali metal and quaternary ammonium ions under conditions of increasing temperature, that the positive transfer image defects resultant from the aforementioned overextended pH maintenance and/or premature pH reduction are obviated.

As examples of polymers which were disclosed to exhibit inverse temperature-dependent permeability to alkali, mention may be made of: hydroxypropyl polyvinyl alcohol, polyvinyl methyl ether, polyethylene oxide, polyvinyl oxazolidone, hydroxypropyl methyl cellulose, isopropyl cellulose, partial acetals of polyvinyl alcohol such as partial polyvinyl butyral, partial polyvinyl formal, partial polyvinyl acetal, partial polyvinyl propional, and the like.

The last-mentioned specified acetals of polyvinyl were stated to generally comprise saturated aliphatic hydrocarbon chains of a molecular weight of at least 1000, preferably of about 1000 to 50,000, possessing a degree of acetilation within about to 10 to 30%, 20 to 80%, and 10 to of the polyvinyl alcoholstheoretical polymeric hydroxy groups, respectively, and including mixed acetals where desired.

Where desired, a mixture of the polymers may be employed, for example, a mixture of hydroxypropyl methyl cellulose and partial polyvinyl butyral.

Employment of the detailed and preferred film units of the present invention, according to the herein described color diffusion transfer process, specifically provides for the production of a highly stable transfer image accomplished, at least in part, by elfectively obviating the previously discussed disadvantages of the prior art products and processes, by in process adjustment of the environmental processing composition solvent and pH concentration from a solvent and pH concentration at which dye diffusion or transfer is operative to a solvent and pH concentration at which dye transfer is inoperative subsequent to substantial transfer image formation. The stable color transfer image is obtained irrespective of the fact that the film unit is maintained as an integral laminate unit during exposure, processing, viewing, and storage of the unit. Accordingly, by means of the present invention, multicolor transfer images may be provided over an extended processing temperature range which exhibit desired maximum and minimum dye transfer image densities; yellow, magenta and cyan dye saturation; red, green and blue hues; and color separation. These unexpected advantages are in addition to the manufacturing advantages obtained by reason of the present invention 5 integral color transfer film unit construction and wh ch will be readily apparent from examination of the units parameters, that is, for example, advantages in more efficient utilization of fabricating materials and components, enhanced simplicity of film manufacture and camera design and construction, and more simplified and effectively controlled customer utilization of the unit.

The dimensionally stable support layers referred to may comprise any of the various types of conventional opaque and transparent rigid or flexible materials possessing the requisite liquid impermeability and vapor transmissivity denoted above, and may comprise polymeric films of both synthetic types and those derived from naturally occurring products. Particularly suitable materials include aqueous alkaline solution impermeable, water vapor permeable, flexible polymeric materials such as vapor permeable polymeric films derived from ethylene glycol terephthalic acid, vinyl chloride polymers; polyvinyl acetate; polyamides; polymethacrylic acid methyl and ethyl esters; cellulose derivatives such as cellulose, acetate, triacetate, nitrate, propionate, butyrate, acetatepropionate, or acetate-butyrate; alkaline solution impermeable, water vapor permeable papers; crosslinked polyvinyl alcohol; regenerated cellulose; and the like.

As examples of materials, for use as the image-receiving layer, mention may be made of solution dyeable polymers such as nylon as, for example, N-methoxymethyl polyhexarnethylene adipamide; partially hydrolyzed polyvinyl acetate; polyvinyl alcohol with or without plasticizers; cellulose acetate with filler as, for example, one-half cellulose acetate and one-half oleic acid; gelatin; and other materials of a similar nature. Preferred materials comprise polyvinyl alcohol or gelatin containing a dye mordant such as poly-4-vinylpyridine, as disclosed in U.S. Pat. No. 3,148,061, issued Sept. 8, 1964.

It will be noted that the liquid processing composition employed may contain an auxiliary or accelerating developing agent, such as p-methylaminophenol, 2,4-diaminophenol, p-benzylaminophenyl, hydroquinone, toluhydroquinone, phenyihydroquinone, 4'-methylphenylhydroquinone, etc. It is also contemplated to employ a plurality f auxiliary or accelerating developing agents, such as a 3- pyrazolidone developing agent and a benzenoid developing agent, as disclosed in US. Pat. No. 3,039,869, issued June 19, 1962. As examples of suitable combinations of auxiliary developing agents, mention may be made of 1- phenyl-3-pyrazolidone in combination with p-benzylaminophenol and 1-phenyl-3-pyrazolidone in combination with 2,5-bis-ethylenimino-hydroquinone. Such auxiliary developing agents may be employed in the liquid processing composition or they may be initially incorporated, at least in part, in any one or more of the silver halide emulsion strata, the strata containing the dye developers, the interlayers, the overcoat layer, the image-receiving layer, or in any other auxiliary layer, or layers, of the film unit. It may be noted that at least a portion of the dye developer oxidized during development may be oxidized and immobilized as a result of a reaction, e.g., an energy-transfer reaction, with the oxidation product of an oxidized auxiliary developing agent, the latter developing agent being oxidized by the development of exposure silver halide. Such a reaction of oxidized developing agent with unoxidized dye developer would regenerate the auxiliary developing agent for further reaction with the exposed silver halide.

In addition, development may be effected in the presence of an onium compound, particularly a quaternary ammonium compound, in accordance with the processes disclosed in US. Pat. No. 3,173,786, issued Mar. 16, 1965.

It will be apparent that the relative proportions of the agents of the diffusion transfer processing composition may be altered to suit the requirements of the operator. Thus, it is within the scope of this invention to modify the herein described developing compositions by the substitution of preservatives, alkalies, etc., other than those specifically mentioned, provided that the pH of the composition is initially at the first pH and solvent concentration required. When desirable, it is also contemplated to include, in the developing composition, components such as restrainers, accelerators, etc. Similarly, the concentration of various components may be varied over a wide range and when desirable adaptable components may be disposed in the photosensitive element, prior to exposure, in a separate permeable layer of the photosensitive element and/or in the photosensitive emulsion.

In all examples of this specification, percentages of components are given by Weight unless otherwise indicated.

An extensive compilation of specific dye developers particularly adapted for employment in photographic diffusion transfer proceses is set forth in aforementioned US. Pat. No. 2,983,606 and in the various copending US. applications referred to in that patent, especially in the table of US. applications incorporated by reference into the patent as detailed in column 27. As examples of additional US. patents detailing specific dye developers for photographic transfer process use, mention may also be made of US Pats. Nos. 2,983,605; 2,992,106; 3,047,386; 3,076,808; 3,076,820; 3,077,402; 3,126,280; 3,131,061; 3,134,762; 3,134,765; 3,135,604; 3,135,605; 3,135,606; 3,135,734; 3,141,772; 3,142,565; and the like.

As additional examples of synthetic film-forming permeable polymers particularly adapted to retain dispersed dye developer, mention may be made of nitrocarboxymethyl cellulose, as disclosed in US. Pat. No. 2,992,104; an acylamidobenzene sulfo ester of a partial sulfobenzal of polyvinyl alcohol, as disclosed in US. Pat. No. 3,043,692; polymers of N-alkyla,,6-unsaturated carboxamides and copolymers of N-alkyl-a,B-carboxamides with N-hydroxyalkyl-a,;8-unsaturated carboxamides, as disclosed in US. Pat. No. 3,069,263; copolymers of vinylphthalimide and mB-unsaturated carboxylic acids, as disclosed in US. Pat. No. 3,061,428; copolymers of N-vinylpyrrolidones and nip-unsaturated carboxylic acids and terpolymers of N-vinylpyrrolidones, cap-unsaturated carboxylic acids and alkyl esters of a ti-unsaturated carboxylic acids, as disclosed in US. Pat. No. 3,044,873; copolymers of N,N-dialkyl-tsp-unsaturated carboxamides with (1,13- unsaturated carboxylic acids, the corresponding amides of such acids, and copolymers of N-aryland N-cycloalkyla ti-unsaturated carboxamides with end-unsaturated carboxylic acids, as disclosed in US. Pat. No. 3,069,296; and the like.

In addition to conventional techniques for the direct dispersion of a particulate solid material in a polymeric, or colloidal, matrix such as ball-milling and the like techniques, the preparation of the dye developer dispersion may also be obtained by dissolving the dye in an appropriate solvent, or mixture of solvents, and the resultant solutiontion distributed in the polymeric binder, with optional subsequent removal of the solvent, or solvents, employed, as, for example, by vaporization where the selected solvent, or solvents, possesses a sufficiently low boiling point or wahing where the selected solvent, or solvents, possesses a sufficiently high differential solubility in the wash medium, for example, water, when measured against the solubility of the remaining composition components, and/or obtained by dissolving both the polymeric binder and dye in a common solvent.

For further detailed treatment of solvent distribution systems of the types refered to above, and for an extensive compilation of the conventional solvents traditionally employed in the art to effect distribution of photographic color-providing materials in polymeric binders, specifically for the formation component layers of photographic film units, reference may be made to US. Pats. Nos. 2,269,158; 2,322,027; 2,304,939; 2,304,940; 2,801,171; and the like.

Although the invention has been discussed in detail throughout employing dye developers, the preferred image-providing materials, it will be readily recognized that other, less preferred, image-providing materials may be substituted in replacement of the preferred dye developers in the practice of the invention. For example, there may be employed dye image-forming materials such as those disclosed in US. Pats. Nos. 2,647,049; 2,661,293; 2,698,244; 2,698,798; 2,802,735; 3,148,062; 3,227,550; 3,227,551; 3,227,552; 3,227,554; 3,243,294; 3,330,655; 3,347,671; 3,352,672; 3,364,022; 3,443,939; 3,443,940; 3,443,941; 3,443,943; etc., wherein color diffusion transfer processes are described which employ color coupling techniques comprising, at least in part, reacting one or more color developing agents and one or more color formers or couplers to provide a dye transfer image to a superposed image-receiving layer and those disclosed in US. Pats. Nos. 2,774,668 and 3,087,817, wherein color diffusion transfer processes are described which employ the imagewise differential transfer of complete dyes by the mechanisms therein described to provide a transfer dye image to a contiguous image-receiving layer, and thus including the employment of image-providing materials in whole or in part initially insoluble or nonditfusible as disposed in the film unit which diffuse during processing as a direct or indirect function of exposure.

Although the preceding description of the invention has been couched in terms of the preferred photosensitive component construction wherein at least two selectively sensitized photosensitive strata are in contiguous coplanar relationship and, specifically, in terms of the preferred tripack type structure comprising a red-sensitive silver halide emulsion stratum, a green-sensitive silver halide emulsion stratum and a blue-sensitive silver halide emulsion stratum having associated therewith, respectively a cyan dye developer, a magenta dye developer and a yellow dye developer, the photosensitive component of the film unit may comprise at least two sets of selectively sensitized minute photosensitive elements arranged in the form of a photosensitive screen wherein each of the minute photosensitive elements has associated therewith, for example, an appropriate dye developer in or behind its respective silver halide emulsion portion. In general, a

suitable photosensitvie screen will comprise minute redsensitized emulsion elements, minute green-sensitized emulsion elements and minute blue-sensitized emulsion elements arranged in side-by-side relationship in a screen pattern and having associated therewith, respectively, a cyan, a magenta and a yellow dye developer.

The present invention also includes the employment of a black dye developer and the use of a mixture of dye developers adapted to provide a black-and-white transfer image, for example, the employment of dye developers of the three subtractive colors in an appropriate mixture in which the quantities of the dye developers are proportioned such that the colors combine to provide black.

Where in the specification, the expression positive image has been used, this expression should not be interpreted in a restrictive sense since it is used primarily for purposes of illustration, in that it defines the image produced on the image-carrying layer as being reversed, in the positive-negative sense, with respect to the image in the photosensitive emulsion layers. As an example of an alternative meaning for positive image, assume that the photosensitive element is exposed to actinic light through a negative transparency. In this case, the latent image in the photosensitive emulsion layers will be a positive and the dye image produced on the image-carrying layer will be a negative. The expression positive image is intended to cover such an image produced on the image-carrying layer.

It will be recognized that, by reason of the preferred film units structural parameters, the transfer image formed upon directed exposure of the film unit to a selected subject and processing, will be a geometrically reversed image of the subject. Accordingly, to provide transfer image formation geometrically nonreversed, exposure of such film unit should be accomplished through an image reversing optical system such a camera posessing an image reversing optical system.

In addition to the described essential layers, it will be recognized that the film unit may also contain one or more subcoats or layers, which, in turn, may contain one or more additives such as plasticizers, intermediate essential layers for the purpose, for example, of improving adhesion, and that any one or more of the described layers may comprise a composite of two or more strata of the same, or different, components and which may be contiguous, or separated from, each other, for example, two or more neutralizing layers or the like, one of which may be disposed intermediate the cyan dye image-forming component retaining layer and the dimensionally stable opaque ayer.

Since certain changes may be made in the above product and process without departing from the scope of the invention herein involved, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. A photographic diffusion transfer color process film unit which comprises a plurality of layers including a direct negative photosensitive layer comprising photosensitive silver halide grains the majority of which possess a substantially uniform grain size within the range of -05 to 3.0 microns having associated therewith dye imageforming material which is diffusible during processing of the unit as a function of the point-to-point degree of said photosensitive layers exposure to incident actinic radiation and a layer adapted to receive dye image-forming material diffusing thereto.

2. A photographic diffusion transfer color process film unit as defined in claim 1 wherein -75% of said photosensitive silver halide grains possess said substantially uniform grain size distribution.

3. A photographic diffusion transfer color process film unit as defined in claim 2 wherein of said pho- 27 tosensitive silver halide grains possess said substantially uniform grain size distribution.

4. A photographic difiusion transfer color process film unit as defined in claim 1 wherein said substantially uniform photosensitive silver halide grains are within i-% of the selected grain size.

5. A photographic diffusion transfer color process film unit as defined in claim 4 including opacifying agent, in a quantity sufficient to mask dye image-forming material associated with said photosensitive silver halide layer, adapted to be disposed intermediate said photosensitive silver halide layer and said layer adapted to receive dye image-forming material diffusing thereto.

6. A photographic diffusion transfer color process film unit as defined in claim 4 including means for contacting said photosensitive silver halide layer with a processing composition possessing a pH at which said dye imageforming material is soluble and dilfusible as a function of the point-to-point degree of said photosensitive silver halide layers exposure to incident actinic radiation.

7. A photographic diffusion transfer color process film unit as defined in claim 6 including means for converting the pH of said processing composition from said pH at which said dye image-forming material is soluble and diffusible as a function of said photosensitive silver halide layers exposure to incident actinic radiation to a second pH at which said dye image-forming material is substantially nondiifusible, subsequent to substantial diffusion of soluhilized dye image-forming material to said layer adapted to receive said dye image-forming material diffusing thereto.

8. A photographic diffusion transfer color process film unit as defined in claim 6 wherein said means for contacting said photosensitive silver halide layer with said processing composition comprises a rupturable container retaining said processing composition positioned extending transverse an edge of the film unit to effect, upon application of compressive pressure to said container, dis charge of said containers processing composition contents into contact with said photosensitive silver halide layer.

9. A photographic diffusion transfer color process film unit as defined in claim 8 wherein said rupturable container retaining said processing composition is adapted, upon application of compressive pressure to the container, to discharge the containers processing composition contents intermediate said photosensitive silver halide layer and the layer adapted to receive dye image-forming material diffusing thereto.

10. A photographic diffusion transfer color process film unit as defined in claim 9 wherein said processing composition includes opacifying agent in a quantity sufficient to mask dye image-forming material associated with said photosensitive silver halide layer.

11. A photographic diffusion transfer color process film unit as defined in claim 10 including a dimensionally stable opaque layer positioned contiguous the surface of said photosensitive silver halide layer opposite said layer adapted to receive dye image-forming material diffusing thereto.

12. A photographic diffusion transfer color process film unit as defined in claim 11 including a dimensionally stable transparent layer positioned contiguous the surface of said layer adapted to receive dye imageforming materialditfusing thereto opposite said photosensitive silver halide layer.

13. A photographic diffusion transfer color process film unit as defined in claim 1 wherein said dye image-forming material is a dye which is a silver halide developing agent.

14. A photographic diffusion transfer color process film unit as defined in claim 1 including a dimensionally stable layer positioned contiguous the surface of said photosensitive silver halide layer opposite said layer adapted to receive dye image-forming material diffusing thereto and additionally including at least two selectively sensitized silver halide layers comprising photosensitive silver halide grains the majority of which possess a substantially uniform grain size distribution within the range of -0.5 to 3.0a and having a dye image-forming material associated therewith.

15. A photographic diffusion transfer color process film unit as defined in claim 14 wherein each of the selectively sensitized silver halide layers possesses predominant spectral sensitivity to separate regions of the spectrum and the dye image-forming material associated with each of said silver halide layers possesses a spectral absorption range subsequent to processing substantially complementary to the predominant sensitivity range of its associated silver halide layer.

16. A photographic diffusion transfer color process film unit as defined in claim 15 wherein each of said selectively sensitized silver halide layers comprises photosensitive silver halide grains of which are Within i- 10% of the selected grain size Within said image of -05 to 3.0g.

17. A photographic diffusion transfer color process film unit as defined in in claim 16 which comprises, in combination:

a photosensitive element including a composite structure containing, as essential layers, a dimensionally stable opaque layer; at least two selectively sensitized silver halide emulsion layers possessing predominant spectral sensitivity to separate regions of the visible electromagnetic spectrum, said silver halide emulsion layers comprising photosensitive silver halide grains wherein of said grains possess a uniform grain size distribution within the range of -0.5 to 3.0;r:-10% of the selected grain size and said emulsion layers have associated therewith a dye which is a silver halide developing agent and is soluble and ditfusible, in alkaline processing composition, at a first pH, possessing a spectral absorption range subsequent to processing substantially complementary to the predominant sensitivity range of its associated emulsion layer; an alkaline solution permeable and dyeable polymeric layer; a polymeric layer possessing acid capacity effective subsequent to substantial dye transfer image formation in said dyeable polymeric layer to reduce alkaline process ing composition possessing said first pH at which said dyes are soluble and difi'usible to a second pH at which said dyes are substantially nonditfusible; a dimensionally stable transparent layer; and means securing the layers in substantially fixed relationship; and

a rupturable container retaining an alkaline processing composition possessing said first pH at which said dyes are soluble and dilfusible and opacifying agent in a quantity sufficient to mask dye associated with said selectively sensitized silver halide emulsion layers, said rupturable container positioned and extending transverse an edge of the photosensitive element to effect unidirectional discharge of the containers alkaline processing composition intermediate the dyeable polymeric layer and the selectively sensitized silver halide emulsion layer next adjacent thereto.

18. A photographic diffusion transfer color process film units as defined in claim 17 adapted to be processed by passage of said unit between a pair of juxtaposed pressure-applying members and which comprises, in combination:

a photosensitive element including a composite structure containing, as essential layers, in sequence, a dimensionally stable alkaline solution impermeable opaque layer; a red-sensitive silver halide emulsion layer having associated therewith cyan dye; a greensensitive silver halide emulsion layer having associated therewith magenta dye; a blue-sensitive silver halide emulsion layer having associated therewith 

